| Reinforced concrete two-way slab-and-beam floor system as a horizontal support system in the building structure,in which the slab,beam and column bear and transfer loads to the vertical load-bearing structure,especially,the slab plays an important role in the whole building structures.It is a reasonable calculation method to analyze the internal forces and deformation of the beam and slab by taking the floor system as a whole.However,due to the complexity of the problem,at present,there is not a more perfect method to calculate the internal force and deflection of two-way slabs considering the interaction of the beam and slab at home and abroad.Based on the existing research results,this paper studies and explores the method of calculating the deflections of the two-way slabs system considering the interaction of the beam and slab,which has a good practical significance.The main contents and achievements of this paper are listed as follows:(1)Based on the existing research results,the calculation formula of the elastic deflection of the two-way slabs system subjected to uniform gravity loads considering the interaction of the beam and slab was simplified.Using finite element analysis software SAP2000,the 33 column-support 9-panels in two-way slab-and-beam floor system models were established and analyzed in elastic state,which consider the side length ratio,the position of panel and the relative rigidity of support beam(the linear rigidity and torsional rigidity),the stiffness of the column and the thickness of the slab.Based on the analysis results,the formula for calculating elastic midspan deflections of the two-way slabs was modified.The simplified formula for calculating the elastic midspan deflection of the two-way slabs was proposed by considering the interaction of the beam and the slab.The result shows that the calculated results are in good agreement with the finite results.(2)Based on the simplified formula for calculating the elastic midspan deflections of the two-way slabs system,The midspan deflections of the interior panel,edge panel and corner panel of two-way slabs system were calculated and compared with the experimental results,where the beam cross-section rigidities were calculated by the method of effective moment of inertia in the ACI standard(ACI 318-14)and the method of short-term rigidity in the Chinese standard(GB 50010-2010).Then,the section rigidity in the calculation formula of the elastic deflection considering the beam-slab interaction was modified,and the formula for calculating the deflection of the two-way slabs was proposed from the occurrence of cracks in beam-slab systems to the yield of longitudinal reinforcement in beams.The result shows that the calculated results of the effective moment of inertia method according to the ACI standard(ACI 318-14)are larger than the experimental values.The results calculated by the Chinese standard(GB 50010-2010)are much larger than the experimental results.The results calculated by the modified section rigidity method proposed in this paper are consistent with the experimental results.However,because of the less relevant test data,the applicability and reliability of the formula presented in this paper remains to be further studied. |
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